Thanks for the inputs up until now! I got more info on this 175 OB Evinrude.<br />The OB is a 1970 175 Evinrude. This engine was before they had seperate oil tanks. He mixes his own gas/oil. My guess is that he has no alarm to indicate incorrect ratio. So I'm back to thinking his Alarm is sounding because of the heat sensors. <br />I know there was suggestions of mitxure sensors and fuel pressure sensors but I don't think this 1970 motor has those. Can anyone educate me on what sensors this older engine has? He can idle around all day long with no alarm. What temp should the heads see? If I put thermal sensors on each Head, what would be considered a 'normal' temp. for the outside surface of the head?
